1. Field of the Invention
This invention relates to windshield wiper blades and, more particularly, to an improved backing strip or flexor for a refill unit for a wiper blade.
2. Description of the Prior Art
In the windshield wiper blade art and, in particular, the wiper blades that have been used almost exclusively for wiping both curved and flat windshields since the invention of John W. Anderson, covered by U.S. Pat. No. 2,596,063, issued on May 6, 1952, the wiper blade assembly has an articulated superstructure movably connected to the end of an oscillating windshield wiper arm. The superstructure has claws slidably connected at spaced apart points to a backing strip of a wiper blade refill unit. The claws of the superstructure engage with the edge of the backing strip so as to apply pressure at said spaced points to the backing strip and, therefore, to the rubber wiping element for cleaning the surface of the windshield as the wiper blade assembly is oscillated across the surface of the windshield.
The blade refil unit is adapted to be replaced when the wiping lip of the wiping element becomes worn or when the resilience of the wiping element decreases to a point that the quality of the wipe on the surface of the windshield is less than efficient. The backing strip for the blade refill unit, in some designs, has a slot running substantially the length of the backing strip which is adapted to bridge the hinge or web between the wiping portion of the wiping element and the bead or head of the wiping element so as to permit the wiping portion of the wiping element to hinge from side-to-side relative to the backing strip. Heretofore, the slot provided in the backing strip of certain designs is too wide, permitting the wiping element to become disengaged from the backing strip which destroys the usefulness of the wiper blade assembly. A design which has suffered from this deficiency is shown in the Scinta U.S. Pat. No. 2,687,544 and the Lenz et al. U.S. Pat. No. 3,153,254.
In addition, in some designs, the backing strip has not been wide enough so that the engagement with the claws of the superstructure is inadequate, resulting in the backing strip becoming disengaged frm the superstructure and, therefore, once again, causing the effectiveness of the wiper blade assembly to be destroyed. The above two cited patents, U.S. Pat. Nos. 3,153,254 and 2,687,544, both suffer from this same dificiency.
In order to hold the wiper refill unit assembled with the superstructure, end clips have been provided, such as is shown by the Lenz et al U.S. Pat. No. 3,153,254, the DePew U.S. Pat. No. 2,983,945 and the Roberts U.S. Pat. No. 3,707,741. Each of the end clips shown in the three mentioned patents have upturned tabs for holding the end clip assembled with the backing strip and have finger engaging portions for providing a purchase for depressing the sides of the end clip so as to facilitate removal of the superstructure from the wiper refill unit.
The wiper refill units of the types of blades just described, have an occasion resulted in scratched windshields due to the rubber wiping element escaping from the backing strip where the slot in the backing strip was too wide. The scratching has also been caused by failure to provide adequate width to the backing strip so that the claws of the superstructure became diengaged from th side edges of the backing strip. Lastly, the end clip could become disengaged from the backing strip whereupon the refil unit separate from the superstructure, resulting in scratching of the windshield.